Sona Geometry from Angola: Mathematics of an African Tradition

Paulus Gerdes's Sona Geometry from Angola, Mathematics of an African Tradition, published by Polimetrica in 2006, is the mathematician and ethnomathematician's study of the sona sand drawings of the Chokwe and neighboring peoples of northeastern Angola, tracing lines drawn in a single continuous movement that encode proverbs, stories and mathematical structure including Eulerian graph properties. Gerdes spent decades developing ethnomathematics as a field specifically to recover the mathematical reasoning embedded in African artistic and technical traditions that earlier scholarship had treated only as decorative. Its strength is that dual competence, reading the drawings as genuine mathematics on their own terms rather than as folk art awaiting Western validation. Its limit is that the sona tradition was disrupted by Angola's long civil war and colonial suppression, so much of Gerdes's reconstruction works from earlier ethnographic records and surviving practitioners rather than an unbroken living tradition, and a claim about the drawings' full ritual context beyond their mathematical structure needs that older ethnographic record directly.